1 files changed, 23 insertions, 0 deletions
diff --git a/js/src/doc/lib/common.sh b/js/src/doc/lib/common.sh
new file mode 100644
index 000000000..785f7dec1
--- /dev/null
+++ b/js/src/doc/lib/common.sh
@@ -0,0 +1,23 @@
+# Common utility functions for js/src/doc scripts.
+
+# `relative BASE ABSOLUTE` prints the URL relative to BASE that is
+# equivalent to ABSOLUTE. BASE must end with a '/'. This function will
+# introduce at most one level of '..'.
+relative() {
+    local parent=$(dirname "$1")
+    case "$2" in
+        "$1"*)
+            # ABSOLUTE is within BASE; just remove BASE.
+            echo "$2" | sed -e "s|^$1||"
+            ;;
+        "$parent/"*)
+            # ABSOLUTE is within BASE/..
+            echo "$2" | sed -e "s|^$parent/|../|"
+            ;;
+        *)
+            # ABSOLUTE is unrelated to BASE.
+            echo "$2"
+            ;;
+    esac
+}
+